Audio output device and method for controlling output speed of audio data thereof

ABSTRACT

An audio output device according to an embodiment may include: a short-range communication module configured to perform short-range wireless communication; a memory configured to buffer audio data received from an external electronic device through the short-range communication module; an audio output unit configured to output the audio data; and a processor. The processor may be configured to: receive operation mode information related to a function being executed in the external electronic device from the external electronic device through the short-range communication module; configure a reference period corresponding to an amount of the audio data buffered in the memory based on the operation mode information; and determine a playback speed of the audio data to be output through the audio output unit by comparing the amount of the buffered audio data with the configured reference period. In addition, various other embodiments may be possible.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. 119 toKorean Patent Application No. 10-2020-0006726, filed on Jan. 17, 2020,in the Korean Intellectual Property Office, the disclosure of which isherein incorporated by reference in its entirety.

BACKGROUND 1) Field

One or more embodiments disclosed herein generally relate to an audiooutput device and, more particularly, to an audio output device capableof outputting audio data transmitted from an external electronic devicevia wireless communication. The embodiments also relate to an outputspeed control method of the audio output device.

2) Description of Related Art

With the development of mobile communication and hardware/softwaretechnologies, portable electronic devices (hereinafter, electronicdevices) such as smartphones can implement various functions. Electronicdevices can provide users with various user experiences by installingand executing various applications. Electronic devices can providesounds generated from various applications for users using audioaccessories connected via a wire or wirelessly. Recently, trends inaudio accessories have been moved from wired connections to wirelessconnections. For example, earphones, headphones, earbuds, speakers, andthe like which are connected to the electronic device throughshort-range wireless communication, such as Bluetooth, are being used.

Such an audio accessory may include a buffer memory and may output audiodata received from the electronic device in the manner offirst-in-first-out. Here, the audio accessory may accumulate a certainlevel of audio data in the buffer memory in order to prevent soundinterruption. Specifically, when the electronic device streams audiodata to the wireless audio accessory, the audio accessory may store aspecified amount of the audio data in the buffer memory rather thanimmediately outputting the audio data, and may then output audio datawhen the specified amount of audio data is accumulated.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Wireless audio accessories do not have the disadvantages of wired audioaccessories but need to overcome the problem of sound interruption in awireless environment and latency in synchronization and real timebetween the sound provided by an audio accessory and when a video isprovided by an electronic device.

For example, the amount of audio data stored in a buffer memory may beconfigured to be high, which may be advantageous to resolving soundinterruption but which may cause the audio and the video displayed bythe electronic device to be desynchronized due to greater latency time.On the contrary, the amount of buffered audio data may be configured tobe low, which may be disadvantageous to resolving sound interruption.

Aspects of certain embodiments disclosed herein is to provide an audiooutput device capable of being optimized for sound interruption and/orlatency, and an audio output speed control method thereof.

An audio output device according to an embodiment may include: ashort-range communication module configured to perform short-rangewireless communication; a memory configured to buffer audio datareceived from an external electronic device through the short-rangecommunication module; an audio output unit configured to output theaudio data; and a processor operatively connected to the short-rangecommunication module, the memory, and the audio output unit, wherein theprocessor may be configured to: receive operation mode informationrelated to a function being executed in the external electronic devicefrom the external electronic device through the short-rangecommunication module; configure a reference period corresponding to theamount of the audio data buffered in the memory based on the operationmode information; and determine the playback speed of the audio data tobe output through the audio output unit by comparing the amount of thebuffered audio data with the configured reference period.

A method for controlling an audio output speed according to anembodiment may include: receiving operation mode information related toa function being executed in an external electronic device from theexternal electronic device through short-range communication;configuring a reference period corresponding to the amount of audio databuffered in a memory based on the operation mode information; anddetermining the playback speed of the audio data to be output through anaudio output unit by comparing the amount of the buffered audio datawith the configured reference period.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosure and its advantages,reference is now made to the following description taken in conjunctionwith the accompanying drawings, in which like reference numeralsrepresent like parts:

FIG. 1 illustrates an electronic device in a network environmentaccording to an embodiment;

FIG. 2A illustrates an example of an audio output device according to anembodiment, and FIG. 2B illustrates an example of an audio output deviceaccording to another embodiment;

FIG. 3 is a block diagram illustrating an audio output device accordingto an embodiment;

FIG. 4 illustrates a buffer memory of an audio output device accordingto an embodiment;

FIG. 5A illustrates an operation with a buffer memory reference periodof an audio output device in a normal mode according to an embodiment,and FIG. 5B illustrates another operation with a buffer memory referenceperiod of an audio output device in a normal mode according to anembodiment;

FIG. 6A illustrates an operation with a buffer memory reference periodof an audio output device in a low latency mode according to anembodiment, and FIG. 6B illustrates another operation with a buffermemory reference period of an audio output device in a low latency modeaccording to an embodiment;

FIG. 7 illustrates a case where a reference period of a buffer memory ofan audio output device is configured in a plurality of levels accordingto an embodiment;

FIG. 8 is a flowchart illustrating a method for controlling an audiooutput speed according to an embodiment;

FIG. 9 is a block diagram illustrating a first audio output device and asecond audio output device according to an embodiment;

FIG. 10 illustrates the operations of an electronic device, a firstaudio output device and a second audio output device according to anembodiment;

FIG. 11 illustrates reference periods of buffer memories of a firstaudio output device and a second audio output device according to anembodiment;

FIG. 12 is a flowchart illustrating a method for controlling an audiooutput speed according to an embodiment; and

FIG. 13 is a flowchart illustrating a method for controlling an audiooutput speed according to an embodiment.

DETAILED DESCRIPTION

Certain embodiments disclosed herein may provide an audio output devicecapable of being optimized for sound interruption and/or latency bydynamically adjusting the capacity of a buffer memory based on theoperation mode of an electronic device wirelessly providing audio data,and an audio output speed control method thereof.

FIG. 1 is a block diagram illustrating an electronic device 101 in anetwork environment 100 according to an embodiment. Referring to FIG. 1,the electronic device 101 in the network environment 100 may communicatewith an electronic device 102 via a first network 198 (e.g., ashort-range wireless communication network), or an electronic device 104or a server 108 via a second network 199 (e.g., a long-range wirelesscommunication network). According to an embodiment, the electronicdevice 101 may communicate with the electronic device 104 via the server108. According to an embodiment, the electronic device 101 may include aprocessor 120, memory 130, an input device 150, a sound output device155, a display device 160, an audio module 170, a sensor module 176, aninterface 177, a haptic module 179, a camera module 180, a powermanagement module 188, a battery 189, a communication module 190, asubscriber identification module (SIM) 196, or an antenna module 197. Insome embodiments, at least one (e.g., the display device 160 or thecamera module 180) of the components may be omitted from the electronicdevice 101, or one or more other components may be added in theelectronic device 101. In some embodiments, some of the components maybe implemented as single integrated circuitry. For example, the sensormodule 176 (e.g., a fingerprint sensor, an iris sensor, or anilluminance sensor) may be implemented as embedded in the display device160 (e.g., a display).

The processor 120 may execute, for example, software (e.g., a program140) to control at least one other component (e.g., a hardware orsoftware component) of the electronic device 101 coupled with theprocessor 120, and may perform various data processing or computation.According to one embodiment, as at least part of the data processing orcomputation, the processor 120 may load a command or data received fromanother component (e.g., the sensor module 176 or the communicationmodule 190) in volatile memory 132, process the command or the datastored in the volatile memory 132, and store resulting data innon-volatile memory 134. According to an embodiment, the processor 120may include a main processor 121 (e.g., a central processing unit (CPU)or an application processor (AP)), and an auxiliary processor 123 (e.g.,a graphics processing unit (GPU), an image signal processor (ISP), asensor hub processor, or a communication processor (CP)) that isoperable independently from, or in conjunction with, the main processor121. Additionally or alternatively, the auxiliary processor 123 may beadapted to consume less power than the main processor 121, or to bespecific to a specified function. The auxiliary processor 123 may beimplemented as separate from, or as part of the main processor 121.

The auxiliary processor 123 may control at least some of functions orstates related to at least one component (e.g., the display device 160,the sensor module 176, or the communication module 190) among thecomponents of the electronic device 101, instead of the main processor121 while the main processor 121 is in an inactive (e.g., sleep) state,or together with the main processor 121 while the main processor 121 isin an active state (e.g., executing an application). According to anembodiment, the auxiliary processor 123 (e.g., an image signal processoror a communication processor) may be implemented as part of anothercomponent (e.g., the camera module 180 or the communication module 190)functionally related to the auxiliary processor 123.

The memory 130 may store various data used by at least one component(e.g., the processor 120 or the sensor module 176) of the electronicdevice 101. The various data may include, for example, software (e.g.,the program 140) and input data or output data for a command relatedthereto. The memory 130 may include the volatile memory 132 or thenon-volatile memory 134.

The program 140 may be stored in the memory 130 as software, and mayinclude, for example, an operating system (OS) 142, middleware 144, oran application 146.

The input device 150 may receive a command or data to be used by othercomponent (e.g., the processor 120) of the electronic device 101, fromthe outside (e.g., a user) of the electronic device 101. The inputdevice 150 may include, for example, a microphone, a mouse, a keyboard,or a digital pen (e.g., a stylus pen).

The sound output device 155 may output sound signals to the outside ofthe electronic device 101. The sound output device 155 may include, forexample, a speaker or a receiver. The speaker may be used for generalpurposes, such as playing multimedia or playing record, and the receivermay be used for an incoming calls. According to an embodiment, thereceiver may be implemented as separate from, or as part of the speaker.

The display device 160 may visually provide information to the outside(e.g., a user) of the electronic device 101. The display device 160 mayinclude, for example, a display, a hologram device, or a projector andcontrol circuitry to control a corresponding one of the display,hologram device, and projector. According to an embodiment, the displaydevice 160 may include touch circuitry adapted to detect a touch, orsensor circuitry (e.g., a pressure sensor) adapted to measure theintensity of force incurred by the touch.

The audio module 170 may convert a sound into an electrical signal andvice versa. According to an embodiment, the audio module 170 may obtainthe sound via the input device 150, or output the sound via the soundoutput device 155 or a headphone of an external electronic device (e.g.,an electronic device 102) directly (e.g., wiredly) or wirelessly coupledwith the electronic device 101.

The sensor module 176 may detect an operational state (e.g., power ortemperature) of the electronic device 101 or an environmental state(e.g., a state of a user) external to the electronic device 101, andthen generate an electrical signal or data value corresponding to thedetected state. According to an embodiment, the sensor module 176 mayinclude, for example, a gesture sensor, a gyro sensor, an atmosphericpressure sensor, a magnetic sensor, an acceleration sensor, a gripsensor, a proximity sensor, a color sensor, an infrared (IR) sensor, abiometric sensor, a temperature sensor, a humidity sensor, or anilluminance sensor.

The interface 177 may support one or more specified protocols to be usedfor the electronic device 101 to be coupled with the external electronicdevice (e.g., the electronic device 102) directly (e.g., wiredly) orwirelessly. According to an embodiment, the interface 177 may include,for example, a high definition multimedia interface (HDMI), a universalserial bus (USB) interface, a secure digital (SD) card interface, or anaudio interface.

A connecting terminal 178 may include a connector via which theelectronic device 101 may be physically connected with the externalelectronic device (e.g., the electronic device 102). According to anembodiment, the connecting terminal 178 may include, for example, a HDMIconnector, a USB connector, a SD card connector, or an audio connector(e.g., a headphone connector).

The haptic module 179 may convert an electrical signal into a mechanicalstimulus (e.g., a vibration or a movement) or electrical stimulus whichmay be recognized by a user via his tactile sensation or kinestheticsensation. According to an embodiment, the haptic module 179 mayinclude, for example, a motor, a piezoelectric element, or an electricstimulator.

The camera module 180 may capture a still image or moving images.According to an embodiment, the camera module 180 may include one ormore lenses, image sensors, image signal processors, or flashes.

The power management module 188 may manage power supplied to theelectronic device 101. According to one embodiment, the power managementmodule 188 may be implemented as at least part of, for example, a powermanagement integrated circuit (PMIC).

The battery 189 may supply power to at least one component of theelectronic device 101. According to an embodiment, the battery 189 mayinclude, for example, a primary cell which is not rechargeable, asecondary cell which is rechargeable, or a fuel cell.

The communication module 190 may support establishing a direct (e.g.,wired) communication channel or a wireless communication channel betweenthe electronic device 101 and the external electronic device (e.g., theelectronic device 102, the electronic device 104, or the server 108) andperforming communication via the established communication channel. Thecommunication module 190 may include one or more communicationprocessors that are operable independently from the processor 120 (e.g.,the application processor (AP)) and supports a direct (e.g., wired)communication or a wireless communication. According to an embodiment,the communication module 190 may include a wireless communication module192 (e.g., a cellular communication module, a short-range wirelesscommunication module, or a global navigation satellite system (GNSS)communication module) or a wired communication module 194 (e.g., a localarea network (LAN) communication module or a power line communication(PLC) module). A corresponding one of these communication modules maycommunicate with the external electronic device via the first network198 (e.g., a short-range communication network, such as Bluetooth™,wireless-fidelity (Wi-Fi) direct, or infrared data association (IrDA))or the second network 199 (e.g., a long-range communication network,such as a cellular network, the Internet, or a computer network (e.g.,LAN or wide area network (WAN)). These various types of communicationmodules may be implemented as a single component (e.g., a single chip),or may be implemented as multi components (e.g., multi chips) separatefrom each other. The wireless communication module 192 may identify andauthenticate the electronic device 101 in a communication network, suchas the first network 198 or the second network 199, using subscriberinformation (e.g., international mobile subscriber identity (IMSI))stored in the subscriber identification module 196.

The antenna module 197 may transmit or receive a signal or power to orfrom the outside (e.g., the external electronic device) of theelectronic device 101. According to an embodiment, the antenna module197 may include an antenna including a radiating element composed of aconductive material or a conductive pattern formed in or on a substrate(e.g., PCB). According to an embodiment, the antenna module 197 mayinclude a plurality of antennas. In such a case, at least one antennaappropriate for a communication scheme used in the communicationnetwork, such as the first network 198 or the second network 199, may beselected, for example, by the communication module 190 (e.g., thewireless communication module 192) from the plurality of antennas. Thesignal or the power may then be transmitted or received between thecommunication module 190 and the external electronic device via theselected at least one antenna. According to an embodiment, anothercomponent (e.g., a radio frequency integrated circuit (RFIC)) other thanthe radiating element may be additionally formed as part of the antennamodule 197.

At least some of the above-described components may be coupled mutuallyand communicate signals (e.g., commands or data) therebetween via aninter-peripheral communication scheme (e.g., a bus, general purposeinput and output (GPIO), serial peripheral interface (SPI), or mobileindustry processor interface (MIPI)).

According to an embodiment, commands or data may be transmitted orreceived between the electronic device 101 and the external electronicdevice 104 via the server 108 coupled with the second network 199. Eachof the electronic devices 102 and 104 may be a device of a same type as,or a different type, from the electronic device 101. According to anembodiment, all or some of operations to be executed at the electronicdevice 101 may be executed at one or more of the external electronicdevices 102, 104, or 108. For example, if the electronic device 101should perform a function or a service automatically, or in response toa request from a user or another device, the electronic device 101,instead of, or in addition to, executing the function or the service,may request the one or more external electronic devices to perform atleast part of the function or the service. The one or more externalelectronic devices receiving the request may perform the at least partof the function or the service requested, or an additional function oran additional service related to the request, and transfer an outcome ofthe performing to the electronic device 101. The electronic device 101may provide the outcome, with or without further processing of theoutcome, as at least part of a reply to the request. To that end, acloud computing, distributed computing, or client-server computingtechnology may be used, for example.

The electronic device according to certain embodiments may be one ofvarious types of electronic devices. The electronic devices may include,for example, a portable communication device (e.g., a smartphone), acomputer device, a portable multimedia device, a portable medicaldevice, a camera, a wearable device, or a home appliance. According toan embodiment of the disclosure, the electronic devices are not limitedto those described above.

It should be appreciated that certain embodiments of the disclosure andthe terms used therein are not intended to limit the technologicalfeatures set forth herein to particular embodiments and include variouschanges, equivalents, or replacements for a corresponding embodiment.With regard to the description of the drawings, similar referencenumerals may be used to refer to similar or related elements. It is tobe understood that a singular form of a noun corresponding to an itemmay include one or more of the things, unless the relevant contextclearly indicates otherwise. As used herein, each of such phrases as “Aor B,” “at least one of A and B,” “at least one of A or B,” “A, B, orC,” “at least one of A, B, and C,” and “at least one of A, B, or C,” mayinclude any one of, or all possible combinations of the items enumeratedtogether in a corresponding one of the phrases. As used herein, suchterms as “1st” and “2nd,” or “first” and “second” may be used to simplydistinguish a corresponding component from another, and does not limitthe components in other aspect (e.g., importance or order). It is to beunderstood that if an element (e.g., a first element) is referred to,with or without the term “operatively” or “communicatively”, as “coupledwith,” “coupled to,” “connected with,” or “connected to” another element(e.g., a second element), it means that the element may be coupled withthe other element directly (e.g., wiredly), wirelessly, or via a thirdelement.

As used herein, the term “module” may include a unit implemented inhardware, software, or firmware, and may interchangeably be used withother terms, for example, “logic,” “logic block,” “part,” or“circuitry”. A module may be a single integral component, or a minimumunit or part thereof, adapted to perform one or more functions. Forexample, according to an embodiment, the module may be implemented in aform of an application-specific integrated circuit (ASIC).

Certain embodiments as set forth herein may be implemented as software(e.g., the program 140) including one or more instructions that arestored in a storage medium (e.g., internal memory 136 or external memory138) that is readable by a machine (e.g., the electronic device 101).For example, a processor (e.g., the processor 120) of the machine (e.g.,the electronic device 101) may invoke at least one of the one or moreinstructions stored in the storage medium, and execute it, with orwithout using one or more other components under the control of theprocessor. This allows the machine to be operated to perform at leastone function according to the at least one instruction invoked. The oneor more instructions may include a code generated by a compiler or acode executable by an interpreter. The machine-readable storage mediummay be provided in the form of a non-transitory storage medium. Wherein,the term “non-transitory” simply means that the storage medium is atangible device, and does not include a signal (e.g., an electromagneticwave), but this term does not differentiate between where data issemi-permanently stored in the storage medium and where the data istemporarily stored in the storage medium.

According to an embodiment, a method according to certain embodiments ofthe disclosure may be included and provided in a computer programproduct. The computer program product may be traded as a product betweena seller and a buyer. The computer program product may be distributed inthe form of a machine-readable storage medium (e.g., compact disc readonly memory (CD-ROM)), or be distributed (e.g., downloaded or uploaded)online via an application store (e.g., PlayStore™), or between two userdevices (e.g., smart phones) directly. If distributed online, at leastpart of the computer program product may be temporarily generated or atleast temporarily stored in the machine-readable storage medium, such asmemory of the manufacturer's server, a server of the application store,or a relay server.

According to certain embodiments, each component (e.g., a module or aprogram) of the above-described components may include a single entityor multiple entities. According to certain embodiments, one or more ofthe above-described components may be omitted, or one or more othercomponents may be added. Alternatively or additionally, a plurality ofcomponents (e.g., modules or programs) may be integrated into a singlecomponent. In such a case, according to certain embodiments, theintegrated component may still perform one or more functions of each ofthe plurality of components in the same or similar manner as they areperformed by a corresponding one of the plurality of components beforethe integration. According to certain embodiments, operations performedby the module, the program, or another component may be carried outsequentially, in parallel, repeatedly, or heuristically, or one or moreof the operations may be executed in a different order or omitted, orone or more other operations may be added.

FIG. 2A illustrates an example of an audio output device according to anembodiment, and FIG. 2B illustrates an example of an audio output deviceaccording to another embodiment.

According to an embodiment, the audio output device may receive digitalaudio data from an electronic device 280 (e.g., the electronic device101 of FIG. 1) using short-range wireless communication and may processthe digital audio data, thereby outputting an audio sound. There is nolimitation as to the configuration of the audio output device, and theaudio output device may be configured as various types of wireless audioaccessories, such as for example one or more speakers, earphones,headphones, or earbuds. The audio output device may include one or moreaudio output units to output an audio sound. According to an embodiment,since the audio output device receives audio data from the electronicdevice 280 using short-range wireless communication, latency may occurdue to wireless transmission with the electronic device 280 and signalprocessing.

FIG. 2A illustrates an embodiment (e.g., earphones) in which two audiooutput units of an audio output device 210 are connected via a cable.Referring to FIG. 2A, the audio output device 210 may include the twoaudio units which a user can wear on ears, and individual components ofthe audio output device 210 may be connected via a cable. Accordingly,an audio signal provided from a processor (not shown) and a buffer (notshown) of the audio output device 210 to each audio output unit may nothave latency due to wireless transmission, signal processing, and thelike.

Although FIG. 2A shows that the audio output device 210 includes twoaudio output units that the user can wear on his or her ears, certainembodiments illustrated herein may be applied to an audio output device210 (e.g., a wireless speaker) having only one audio output unit.

An embodiment in which an audio output device 210 includes only oneaudio output unit or a plurality of audio output units connected to eachother via a cable will be described in detail with reference to FIG. 3to FIG. 8.

FIG. 2B illustrates an embodiment (e.g., earbuds) in which an audiooutput device 220 includes a first audio output device 220 a and asecond audio output device 220 b which are physically and electricallyseparated from each other. Referring to FIG. 2B, the first audio outputdevice 220 a and the second audio output device 220 b may transmit andreceive audio data to and from each other using short-range wirelesscommunication. Since the first audio output device 220 a and the secondaudio output device 220 b are wirelessly connected, not only latency mayoccur due to short-range wireless communication with the electronicdevice 280 but the output timings of audio data output from the firstaudio output device and audio data output from the second audio outputdevice may also not match. Accordingly, the first audio output device220 a may operate as a master, and the second audio output device 220 bmay operate as a slave, thereby synchronizing the output timings of theoutput audio data with each other.

The embodiment in which the audio output device 220 includes a pluralityof audio output devices 220 a and 220 b that are physically separatedand are wirelessly connected to each other will be described in detailwith reference to FIG. 9 to FIG. 13. However, the embodiment describedwith reference to FIG. 3 to FIG. 8 and the embodiment described withreference to FIG. 9 to FIG. 13 are not independent of each other,technical features illustrated in FIG. 3 to FIG. 8 may also be appliedto the embodiment described with reference to FIG. 9 to FIG. 13, andtechnical features illustrated in FIG. 9 to FIG. 13 may also be appliedto the embodiment described with reference to FIG. 3 to FIG. 8.

Hereinafter, certain embodiments in which the different types of audiooutput devices as illustrated in FIG. 2A and FIG. 2B are optimized forsound interruption and/or latency by dynamically adjusting the capacityof the buffer memory based on the operating mode of the electronicdevice providing the audio data are described.

FIG. 3 is a block diagram illustrating an audio output device accordingto an embodiment.

Referring to FIG. 3, the audio output device 300 according to anembodiment may include a short-range communication module 310, an audiooutput unit 320, a processor 330, and a memory 340. At least some of theillustrated components can be omitted or substituted while stillimplementing the various embodiments disclosed herein. The audio outputdevice 300 may be configured as the audio output device (e.g., earphonesor headphones) 210 illustrated in FIG. 2A.

According to an embodiment, the short-range communication module 310 mayinclude various components, such as an antenna for performingshort-range wireless communication, an RF front end, or a communicationprocessor. Short-range wireless communication supported by theshort-range communication module 310 may include, for example,Bluetooth. Further, standard or nonstandard communication methods may beused without limitation.

The short-range communication module 310 may receive audio data from anelectronic device (e.g., the electronic device 101 of FIG. 1) usingshort-range wireless communication and may transmit information aboutthe operation state of the audio output device 300 (e.g., a batterystate) and the like to the electronic device.

According to an embodiment, the audio output unit 320 may output audiodata buffered in the memory 340 according to control of the processor330. The audio output device 300 may include at least one audio outputunit 320. For example, when the audio output device 300 includes twoaudio output units as shown in FIG. 2A, each audio output unit 320 maybe connected to the processor 330 and the memory 340 via a cable.

According to an embodiment, the memory 340 may buffer the audio datareceived from the electronic device through the short-rangecommunication module 310. The electronic device may transmit generatedaudio data to the audio output device 300 in real time, and audio datareceived by the audio output device 300 may be sequentially storedtemporarily in the memory 340 and then output through the audio outputunit 320. The audio output device 300 may output the audio data in themanner of first-in-first-out, and the outputted audio data may bedeleted from the memory 340. In this document, the amount of audio databuffered in the memory 340 will be described in time units (e.g., ms).

According to an embodiment, the audio output device 300 may output theaudio data received from the electronic device in real time through theaudio output unit 320 according to a streaming method. In this case, theaudio output device 300 may not immediately output the received audiodata, but may store a predetermined amount of audio data in the memory340 and may output the audio data when the predetermined amount of audiodata is accumulated.

Since the audio output device 300 receives the audio data from theelectronic device through short-range wireless communication, soundinterruption may occur due to buffer underrun caused by a change in thewireless environment. Accordingly, the audio output device 300 maybuffer a predetermined amount of audio data in the memory 340.

According to an embodiment, the audio output device 300 includes twoaudio output units as shown in FIG. 2A and FIG. 2B, and the user canhear the output sound by closely placing each audio output unit 320 nearor in both of his or her ears. Audio sounds output from the two audiooutput units 320 may be the same, and different audio sounds may beoutput in stereo.

According to an embodiment, the processor 330 may function to controleach component of the audio output device 300. To this end, theprocessor 330 may be electrically, functionally, and/or operativelyconnected to each component of the audio output device 300, such as theshort-range communication module 310, the audio output unit 320, and thememory 340. The processor 330 may include a microprocessor or anysuitable type of processing circuitry, such as one or moregeneral-purpose processors (e.g., ARM-based processors), a DigitalSignal Processor (DSP), a Programmable Logic Device (PLD), anApplication-Specific Integrated Circuit (ASIC), a Field-ProgrammableGate Array (FPGA), a Graphical Processing Unit (GPU), a video cardcontroller, etc. In addition, it would be recognized that when a generalpurpose computer accesses code for implementing the processing shownherein, the execution of the code transforms the general purposecomputer into a special purpose computer for executing the processingshown herein. Certain of the functions and steps provided in the Figuresmay be implemented in hardware, software or a combination of both andmay be performed in whole or in part within the programmed instructionsof a computer. No claim element herein is to be construed under theprovisions of 35 U.S.C. § 112(f), unless the element is expresslyrecited using the phrase “means for.” In addition, an artisanunderstands and appreciates that a “processor” or “microprocessor” maybe hardware in the claimed disclosure. Under the broadest reasonableinterpretation, the appended claims are statutory subject matter incompliance with 35 U.S.C. § 101.

According to an embodiment, the processor 330 may configure a referenceperiod corresponding to the amount of the audio data buffered in thememory 340. The reference period may include an upper limit and a lowerlimit of the amount of the buffered audio data. For example, thereference period may have a range from about 100 ms to about 400 ms inthe normal mode to be described later, may have a range from about 40 msto about 120 ms in the low latency mode, and may have a range from about150 ms to 600 ms in the high latency mode. The reference period in eachmode may be changed by configuring the audio output device 300 at thetime of manufacture or by user input.

According to an embodiment, the processor 330 may dynamically change thereference period. As described above, the audio output device 300buffers the audio data in the memory 340 in order to prevent soundinterruption, and time taken to accumulate the audio data in the memory340 may be a significant cause of audio output latency. For example,when the electronic device outputs video data and audio datarespectively through a display of the electronic device and the audiooutput device 300 according to operations of a video playbackapplication, since the audio data is buffered in the memory 340 of theaudio output device 300, delay time in outputting the audio data by theaudio output device 300 may occur with respect to output of the videodata by the display of the electronic device. That is, there is atrade-off relationship between the risk of sound interruption due tobuffer underrun and latency in audio output. According to an embodiment,the processor 330 may dynamically change the amount of buffered audiodata, that is, the reference period, according to the operation mode ofthe electronic device transmitting audio data, thereby performingseamless buffer management according to the operation state of theelectronic device and the user's intention.

According to an embodiment, the processor 330 may receive operation modeinformation related to the function currently executed by the electronicdevice from the electronic device through the short-range communicationmodule 310. For example, the operation mode may include a normal mode, alow latency mode, and a high latency mode.

The low latency mode may refer to a state in which the electronic deviceis executing a function (or application) for which real-time operationis important. For example, when the electronic device is executing anapplication, such as a game application, that requires user's touchinput feedback in real time, the electronic device may operate in thelow latency mode. When a game application is being actively executed inthe foreground, the electronic device may determine to operate in thelow latency mode, in which case a framework may receive and processinformation being executed in the game application. Alternatively, whena touch input is continuously received on the display of the electronicdevice or a screen of the electronic device that is turned on, it isexpected that the distance between the audio output device 300 and theelectronic device is very close and accordingly the wireless environmentis good. Thus, the electronic device may operate in the low latencymode.

The high latency mode may operate when decrease in sound interruption ismore important than real-time operation. For example, when the userlistens to music via a music application while the electronic deviceplaced in a bag or pocket, sound interruption due to the increase in thephysical distance between the electronic device and the audio outputdevice 300 may be more significantly considered than the latency inaudio output.

The normal mode may refer to an operation mode for general situationsother than the low latency mode and the high latency mode. For example,when absolutely low latency is not necessary unlike for gameapplications but some low latency is required to provide adequate soundeffect feedback for, for example, user input on buttons during the timewhen the user is listening to music, a certain degree of low latency maybe needed.

According to an embodiment, the electronic device may transmit theoperation mode information to the audio output device 300 when initiallypairing with the audio output device 300, when initially transmittingaudio data, and/or periodically. In addition, when the operation mode ischanged from the normal mode to the low latency mode or from the lowlatency mode to the normal mode due to execution of an application, theelectronic device may transmit operation mode information to the audiooutput device 300.

According to an embodiment, the processor 330 may configure thereference period corresponding to the amount of the audio data bufferedin the memory 340 based on the operation mode information received fromthe electronic device. Since real-time operation is prioritized in thelow latency mode, it is necessary to reduce the amount of the audio databuffered in the memory 340 compared to that in the normal mode.Therefore, the lower limit (e.g., about 40 ms) of the reference periodin the low latency mode may be lower than the lower limit (e.g., about100 ms) of the reference period in the normal mode, and the upper limit(e.g., about 120 ms) of the reference period in the low latency mode maybe lower than the upper limit (e.g., 400 ms) of the reference period inthe normal mode. In addition, since decrease in the risk of soundinterruption is more important than real-time operation (or latency) inthe high latency mode, it is necessary to increase the amount of theaudio data buffered in the memory 340 compared to that in the normalmode. Therefore, the lower limit (e.g. 150 ms) of the reference periodin high latency mode may be greater than the lower limit of thereference period in the normal mode, and the upper limit (e.g. 600 ms)of the reference period in the high latency mode may be greater than theupper limit of the reference period in the normal mode.

According to an embodiment, the processor 330 may determine the playbackspeed of audio data to be output through the audio output unit 320 bycomparing the amount of the buffered audio data with the configuredreference period. For example, when the amount of the buffered audiodata is greater than the upper limit of the reference period, theprocessor 330 may play (or acceleratedly play) the audio data at a speedfaster than a reference speed. When acceleratedly playing the audio datafor a certain period of time, the amount of audio data output throughthe audio output unit 320 and deleted from the memory 340 would begreater than the amount of audio data received from the electronicdevice and accumulated in the memory 340. Thus, the amount of audio databuffered in the memory 340 may be reduced due to the accelerated play.In addition, when the amount of the buffered audio data is less than thelower limit of the reference period, the processor 330 may play (ordeceleratedly play) the audio data at a speed slower than the referencespeed. When deceleratedly playing the audio data for a certain period oftime, the amount of audio data output through the audio output unit 320and deleted from the memory 340 is smaller than the amount of audio datareceived from the electronic device and accumulated in the memory 340.Thus, the amount of audio data buffered in the memory 340 may beincreased due to the decelerated play. As described above, whenaccelerated play or decelerated play is performed for a certain periodof time, the amount of the buffered audio data may be adjusted to bewithin the reference period. Changes in the amount of audio data duringaccelerated playback and decelerated playback in each mode will bedescribed in more detail with reference to FIG. 5A to FIG. 7.

According to an embodiment, when the mode is changed, the processor 330may configure the reference period according to the changed operationmode and may determine the playback speed of audio data by comparing theamount of the buffered audio data with the configured reference period.For example, in a change from the high latency mode or the normal modeto the low latency mode, when the amount of audio data currentlybuffered in the memory 340 is greater than the upper limit of the secondreference period of the low latency mode, the processor 330 mayaccelerate playback of the audio data, thereby reducing the amount ofthe buffered audio data. In a change from the low latency mode to thenormal mode, when the amount of audio data currently buffered in thememory 340 is less than the lower limit of the first reference period ofthe normal mode, the processor 330 may decelerate playback of audiodata, thereby increasing the amount of the buffered audio data.

According to an embodiment, the processor 330 may perform playback atthe original constant speed after a lapse of a predetermined time fromthe accelerated playback or decelerated playback, or may performplayback at the original constant speed when the amount of bufferedaudio data is changed to be within the reference period.

For example, when the mode is changed, the processor 330 may compare theamount of audio data buffered in the memory 340 with a reference period(e.g., the first reference period or the second reference period) of thechanged mode (e.g., the normal mode or the low latency mode), and mayaccelerate or decelerate playback of audio data for a set time (e.g.,five seconds) and may then switch to the normal playback. Here, theprocessor 330 may accelerate or decelerate the playback for apredetermined time, or may calculate time to reach the upper or lowerlimit of the reference period in the accelerated playback or deceleratedplayback in view of the difference between the amount of audio datacurrently buffered in the memory 340 and the upper or lower limit of thereference period and may then accelerate or decelerate the playback fora set time. Here, time for accelerated playback or decelerated playbackmay be in seconds (e.g., ms) or in the unit of a time index assigned toeach piece of audio data.

According to another embodiment, in a change from the high latency modeor the normal mode to the low latency mode, when the amount of bufferedaudio data is reduced to reach the upper limit of the reference period(e.g., the second reference period) after accelerated playback of audiodata, the processor 330 may terminate the accelerated playback and mayplay audio data at the reference speed. In a change from the low latencymode to the normal mode, when the amount of buffered audio data isincreased to reach the lower limit of the reference period (e.g., thefirst reference period) after decelerated playback of audio data, theprocessor 330 may terminate the decelerated playback and may play audiodata at the reference speed.

According to an embodiment, the processor 330 may accelerate ordecelerate the playback at a set speed during the accelerated playbackor the decelerated playback. For example, the processor 330 may playaudio data by about 1.1 times the reference speed in the acceleratedplayback, and may play audio data by about 0.9 times the reference speedin the decelerated playback. Since the difference between the referencespeed and the acceleration or deceleration is not significant, the usermay not recognize the change in the playback speed.

According to an embodiment, the processor 330 may adjust the playbackspeed in a plurality of levels during the accelerated playback ordecelerated playback. For example, in the low latency mode, theprocessor 330 may divide the second reference period into aconstant-speed period ranging from a first lower limit to a first upperlimit and an alert period ranging from a second lower limit to a secondupper limit excluding the constant-speed period (e.g., from the secondlower limit to the first lower limit and from the first upper limit tothe second upper limit). Here, the second lower limit may be lower thanthe first lower limit, and the second upper limit may be greater thanthe first upper limit. In a change from the high latency mode or thenormal mode to the low latency mode, the processor 330 may play audiodata at the reference speed when the amount of buffered audio data iswithin the constant-speed period, may accelerate playback of audio databy first-number times (e.g., 1.1 times) the reference speed when theamount of buffered audio data is within the alert period, and mayaccelerate playback of audio data by second-number times (e.g., 1.2times) the reference speed when the amount of buffered audio dataexceeds the reference period. The second-number may be greater than thefirst-number.

This embodiment will be described in more detail with reference to FIG.7.

According to an embodiment, in accelerated playback of audio data, theelectronic device may acceleratedly process the audio data and maytransmit the audio data to the audio output device 300. In deceleratedplayback of audio data, the audio output device 300 may deceleratedlyprocess and output the audio data.

In accelerated playback, processing in the electronic device isadvantageous in terms of not only latency but also sound interruptionsince the amount of information to be transmitted to the audio outputdevice 300 within a unit time is reduced. On the contrary, indecelerated playback, processing in the electronic device isdisadvantageous because the amount of information to be transmitted tothe audio output device 300 within a unit time is increased.

According to an embodiment, when switching from the high latency mode orthe normal mode to the low latency mode, the electronic device maytransmit audio data to be acceleratedly played for a specified period oftime to the audio output device 300 according to an increased tick.Here, the reason to increase the tick for transmitting audio data isthat increasing the tick is advantageous in terms of decreasing theamount of data that need to be transmitted wirelessly from theelectronic device to the audio output device 300, which may have apositive effect on sound interruption. In addition, data in the buffermemory 340 of the audio output device 300 is exhausted rather than thatin a buffer memory of the electronic device, thereby reducing latency inoutputting audio data.

This embodiment will be described in more detail with reference to FIG.13.

According to an embodiment, when the audio output device 300 acceleratesor decelerates playback of audio data, the accelerated or deceleratedplayback speed may be determined according to an algorithm enablingpitch to remain unchanged, and thus the user may not experiencediscomfort due to the accelerated or decelerated playback. For example,audio signals may be reduced (in acceleration) or increased (indeceleration) in the temporal domain while retaining spectralcharacteristics before acceleration or deceleration. Reducing orincreasing audio signals in the temporal domain may change pitchcharacteristics or may allow the use to hear slow-motion sound, andusing spectral characteristic information already stored makes itpossible to maintain the pitch of the original sound, which reducesaudio deformation.

FIG. 4 illustrates a buffer memory of an audio output device accordingto an embodiment.

According to an embodiment, the audio output device (e.g., the audiooutput device 300 of FIG. 3) may store, in a memory 340, audio datareceived from an electronic device 490 (e.g., the electronic device 101of FIG. 1) through short-range wireless communication (e.g., Bluetooth).

The audio data received by the audio output device may be sequentiallystored temporarily in the memory 340 and then output through an audiooutput unit. The audio output device may output audio data in the mannerof first-in-first-out, and the output audio data may be deleted from thememory 340 once they are outputted.

According to an embodiment, a processor (e.g., the processor of FIG. 3)may configure a reference period of the memory 340. Referring to FIG. 4,the reference period may be configured to be a value between a lowerlimit 341 (or level 1) and an upper limit 342 (or level 2) of thecapacity of the memory 340.

When the electronic device 490 is paired with the audio output deviceand then transmits audio data to the audio output device using wirelessstreaming, the audio output device may output audio data through theaudio output unit (e.g., the audio output unit of FIG. 3) after theamount of buffered audio data reaches the lower limit 341 of thereference period or a specified value between the lower limit 341 andthe upper limit 342, rather than immediately outputting audio data.

Accordingly, even when audio data is not normally received due to thedegradations in the wireless environment, buffered audio data makes itpossible to prevent sound interruption.

FIG. 5A illustrates one operation with a buffer memory reference periodof an audio output device in a normal mode according to an embodiment,and FIG. 5B illustrates another operation with a buffer memory referenceperiod of an audio output device in a normal mode according to anembodiment.

According to an embodiment, the audio output device (e.g., the audiooutput device 300 of FIG. 3) may receive operation mode informationrelated to a function being executed in an electronic device (e.g., theelectronic device 101 of FIG. 1) from the electronic device. Forexample, the operation mode may include a normal mode, a low latencymode, and a high latency mode. The normal mode may refer to an operationmode for situations other than the low latency mode, in which decreasein sound interruption is more important than low latency, such as a casewhere a music application for which real-time operation is not importantis being executed.

According to an embodiment, when the operation mode information receivedfrom the electronic device is the normal mode, the audio output devicemay configure a reference period of a buffer memory 540 as a firstreference period. For example, the lower limit 541 of the firstreference period may be configured to be about 100 ms, and the upperlimit 542 may be configured to be about 400 ms. But the instantdisclosure is not so limited. In a change from the low latency mode tothe normal mode, the audio output device may compare the amount ofbuffered audio data with the reference period.

Referring to FIG. 5A, the capacity 551 of buffered audio data may belower than the lower limit 541 (or level 1) of the reference period. Inthis case, the audio output device may perform decelerated playback ofaudio data at an output speed slower than a reference speed. Since theamount of audio data received from the electronic device per time isgreater than the amount of audio data output through the audio outputdevice due to the decelerated playback, the amount of buffered audiodata may increase.

The audio output device may perform the decelerated playback for aspecified time period or until the amount of buffered audio data reachesthe lower limit 541 of the reference period.

Referring to FIG. 5B, the capacity 552 of buffered audio data may begreater than the upper limit 542 (or level 2) of the reference period.In this case, the audio output device may perform accelerated playbackof audio data at an output speed higher than the reference speed. Sincethe amount of audio data received from the electronic device per time issmaller than the amount of audio data output through the audio outputdevice due to the accelerated playback, the amount of buffered audiodata may decrease.

FIG. 6A illustrates an operation with a buffer memory reference periodof an audio output device in a low latency mode according to anembodiment, and FIG. 6B illustrates another operation with a buffermemory reference period of an audio output device in a normal modeaccording to an embodiment.

According to an embodiment, when an electronic device (e.g., theelectronic device 101 of FIG. 1) operates in the low latency mode, theaudio output device (e.g., the audio output device 300 of FIG. 3) mayconfigure a second reference period corresponding to the low latencymode based on operation mode information received from the electronicdevice. The low latency mode may refer to a state in which theelectronic device is executing a function (or application) for whichreal-time operation is important. For example, when the electronicdevice is executing an application, such as a game application, thatrequires user's touch input feedback in real time, the electronic devicemay operate in the low latency mode. When a game application is beingactively executed in the foreground, the electronic device may determineto operate in the low latency mode, in which case a framework mayreceive and process information being executed in the game application.Alternatively, when a touch input is continuously received on thedisplay of the electronic device or a screen of the electronic devicethat is turned on, it is expected that the distance between the audiooutput device and the electronic device is very close and accordingly awireless environment is good. Thus, the electronic device may operate inthe low latency mode.

According to an embodiment, when the operation mode information receivedfrom the electronic device is the low latency mode, the audio outputdevice may configure a reference period of the buffer memory 640 as asecond reference period. For example, the lower limit (or level 1) ofthe second reference period may be configured to be about 40 ms, and theupper limit (or level 2) thereof may be configured to be about 120 ms.But the instant disclosure is not so limited. In a change from a normalmode to the low latency mode, the audio output device may compare theamount of buffered audio data with the reference period.

Referring to FIG. 5A and FIG. 6A, the same audio data capacity 651 isless than the lower limit 541 of the reference period in the normalmode, but may be within the reference period in the low latency modesince the lower limit 641 of the reference period in the low latencymode is lower than that in the normal mode. Accordingly, in FIG. 6A, theaudio output device may maintain playback of audio data at the constantspeed in the low latency mode.

Referring to FIG. 5B and FIG. 6B, for the same audio data capacity 652,the same capacity may have exceeded the reference period in the lowlatency mode to a greater extent than in the normal mode. Accordingly,in FIG. 6B, the audio output device may accelerate playback of audiodata for a longer time until the audio data capacity reaches the upperlimit 642 of the reference period as compared to the normal mode.

According to an embodiment, when the electronic device operates in ahigh latency mode, the audio output device may configure a thirdreference period corresponding to the high latency mode based on theoperation mode information received from the electronic device. Here,the lower limit (e.g., about 150 ms) of the third reference period maybe higher than the lower limit of the first reference period in thenormal mode and the lower limit of the second reference period in thelow latency mode, and the upper limit (e.g., about 600 ms) of the thirdreference period may be higher than the upper limit of the firstreference period in the normal mode and the upper limit of the secondreference period in the low latency mode.

FIG. 7 illustrates a case where a reference period of a buffer memory ofan audio output device is configured in a plurality of levels accordingto an embodiment.

According to an embodiment, the audio output device (e.g., the audiooutput device 300 of FIG. 3) may adjust a playback speed in a pluralityof levels in accelerated playback or decelerated playback.

Referring to FIG. 7, a second lower limit (or level 1) 741, a firstlower limit (or level 2) 742, a first upper limit (or level 3) 743, anda second upper limit (or level 4) 744 may be configured for the capacityof the buffer memory 740, a period ranging from the first lower limit742 to the first upper limit 743 may be configured as the constant-speedperiod, and a period ranging from the second lower limit 741 to thesecond upper limit 744 excluding the constant-speed period (e.g., fromthe second lower limit 741 to the first lower limit 742 and from thefirst upper limit 743 to the second upper limit 744) may be configuredas an alert period.

According to an embodiment, the audio output device may identify theamount of audio data currently buffered in the memory 740, and maymaintain the playback speed of audio data at the reference speed whenthe amount of the audio data belongs to the constant-speed period (fromthe first lower limit 742 to the first upper limit 743). When the amountof the currently buffered audio data ranges from the second lower limit741 to the first lower limit 742 in the alert period, the audio outputdevice may output audio data at a first deceleration (e.g., 0.9 timesthe reference speed) 751, and when the amount of the currently bufferedaudio data ranges from the first upper limit 743 to the second upperlimit 744, the audio output device may output audio data at a firstacceleration (e.g., 1.1 times the reference speed) 754. When the amountof the buffered audio data is less than or equal to the second lowerlimit 741 outside the reference period, the audio output device mayoutput audio data at a second deceleration (e.g., 0.8 times speed thereference speed) 752, and when the amount of the buffered audio data isequal to or greater than the second upper limit 744, the audio data mayoutput audio data at a second acceleration (e.g., 1.2 times thereference speed) 755.

According to an embodiment, when outputting audio data at the secondacceleration (e.g., 1.2 times the reference speed) 755, the audio outputdevice may reduce the output speed to the first acceleration (e.g., 1.1times the reference speed) 754 if the amount of the buffered audio datareaches the second upper limit 744, and may output audio data at theconstant speed 753 if the amount of the buffered audio data reaches thefirst upper limit 743. Alternatively, the audio output device may outputaudio data at the second acceleration 755 until the amount of the audiodata reaches the first upper limit 743 in the constant-speed period.

FIG. 8 is a flowchart illustrating a method for controlling an audiooutput speed according to an embodiment.

The method illustrated in FIG. 8 may be performed by the audio outputdevice (e.g., the audio output device 300 of FIG. 3) described abovewith reference to FIG. 3 to FIG. 7, and a description of the technicalfeatures described above will be omitted below.

In operation 810, the audio output device may receive operation modeinformation related to a function being executed in an electronic device(e.g., the electronic device 101 of FIG. 1) from the electronic devicethrough a short-range communication module (e.g., the short-rangecommunication module 310 of FIG. 3). For example, the operation mode mayinclude a normal mode and a low latency mode. The electronic device maytransmit the operation mode information to the audio output device wheninitially pairing with the audio output device, when initiallytransmitting audio data, and/or periodically.

In operation 820, the audio output device (e.g., the processor 330 ofFIG. 3) may identify whether the operation mode of the electronic deviceis the low latency mode. Here, the low latency mode may be configured inat least one of the following instances: when the electronic deviceexecutes a specified application (e.g., a game application), when adisplay of the electronic device is turned on, or when the electronicdevice receives a touch input on the display. In addition, the lowlatency mode may be configured in various situations in which real-timeoperation is important.

When the current operation mode is the low latency mode in operation820, the audio output device may configure the reference period as asecond reference period in operation 830.

In operation 825, the audio output device may determine whether theoperation mode of the electronic device is a high latency mode. Here,the high latency mode may be configured when decrease in the risk ofsound interruption is more important than latency in audio output (e.g.,when the electronic device is distant from the audio output device witha music application being executed).

When the current operation mode is the high latency mode in operation825, the audio output device may configure the reference period as athird reference period in operation 840.

When the current operation mode is the normal mode (e.g., when theoperation mode is not the low latency mode in operation 820 and when theoperation mode is not the high latency mode in operation 825), the audiooutput device may configure the reference period corresponding to theamount of audio data buffered in the memory as a first reference periodin operation 845.

In operation 850, the audio output device may receive and identify theamount of audio data currently buffered in the memory (e.g., the memory340 of FIG. 3).

In operation 860, the audio output device may identify whether theamount of the buffered audio data is greater than an upper limit of thereference period (e.g., the first reference period, the second referenceperiod, or the third reference period).

When the amount of the buffered audio data is greater than the upperlimit of the reference period, the audio output device may performaccelerated playback of audio data in operation 882. Here, the audiooutput device may accelerate playback of audio data for a set time(e.g., about five seconds) and may then play audio data at the referencespeed (e.g. normal speed), or may accelerate playback of audio datauntil the amount of the buffered audio data is reduced to reach theupper limit of the reference period.

In operation 870, the audio output device may identify whether theamount of the buffered audio data is smaller than a lower limit of thereference period.

When the amount of the buffered audio data is smaller than the lowerlimit of the reference period, the audio output device may performdecelerated playback of audio data in operation 884. Here, the audiooutput device may decelerate playback of audio data for a set time andmay then play audio data at the reference speed, or may decelerateplayback of audio data until the amount of the buffered audio data isincreased to reach the lower limit of the reference period.

When the amount of the buffered audio data is within the referenceperiod, the audio output device may continuously play audio data at thereference speed (e.g. normal speed) in operation 886.

FIG. 9 is a block diagram illustrating a first audio output device and asecond audio output device according to an embodiment.

FIG. 9 illustrates components of an audio output device in an embodimentin which the audio output device (e.g., the audio output device 220 ofFIG. 2B) includes a first audio output device 920 and a second audiooutput device 940 which are physically and electrically separated.Hereinafter, a description of the technical features described abovewith reference to FIG. 3 to FIG. 8 will be omitted below. The audiooutput device may be configured as earbuds illustrated in FIG. 2B.

Referring to FIG. 9, the audio output device according to an embodimentmay include the first audio output device 920 and the second audiooutput device 940. The first audio output device 920 may include a firstshort-range communication module 921, a first audio output unit 922, afirst processor 923, and a first memory 924, and the second audio outputdevice 940 may include a second short-range communication module 941, asecond audio output unit 942, a second processor 943, and a secondmemory 944. The first audio output device 920 may be worn on the user'sright ear, the second audio output device 940 may be worn on the user'sleft ear, and the first audio output device 920 and the second audiooutput device 940 may have the same or corresponding external shape.

According to an embodiment, the first audio output device 920 mayoperate as a master, and the second audio output device 940 may operateas a slave. For example, the first audio output device 920 may receiveaudio data from an electronic device and may transmit audio data andreference time information for audio output timing synchronization tothe second audio output device 940. According to another embodiment, thefirst audio output device 920 and the second audio output device 940 mayeach receive audio data from the electronic device.

According to an embodiment, the first audio output device 920 may bufferfirst audio data received from the electronic device in the first memory924 and may output audio data through the first audio output unit 922.The second audio output device 940 may buffer second audio data receivedfrom the electronic device or the first audio output device 920 in thesecond memory 944 and may transmit audio data through the second audiooutput unit 942.

Since the first audio output device 920 and the second audio outputdevice 940 are wirelessly connected, both audio output timingsynchronization and the possibility of buffer underrun need to beconsidered when adjusting the audio playback speed. For example, theremay be a scenario in which the first audio output device 920 may performaccelerated playback of audio data and the second audio output device940 may play audio data at a slower speed, and when different amounts ofaudio data are buffered respectively in the first memory 924 and thesecond memory 944, sound interruption may occur due to buffer underrunin one of the first memory 924 or the second memory 944 may occur whenit has a lower buffer level but still is in accelerated playback. Tothis end, the audio output device may perform comparison with areference speed and playback speed control in view of both the capacityof the first memory 924 and the capacity of the second memory 944 inorder to prevent buffer underrun while synchronizing the output timingsof the first audio output unit 922 and the second audio output unit 942.

The audio output device according to an embodiment may configure areference period in consideration of both the amount of audio databuffered in the first memory 924 of the first audio output device 920and the amount of audio data buffered in the second memory 944.

According to an embodiment, the first processor 923 may receive theamount of the second audio data buffered in the second memory 944 fromthe second short-range communication module 941 through the firstshort-range communication module 921. In addition, the first processor923 may identify the amount of the first audio data buffered in thefirst memory 924. The first processor 923 may compare the lower of theamount of the first audio data buffered in the first memory 924 and theamount of the second audio data buffered in the second memory 944 withthe reference period.

According to an embodiment, the first processor 923 may transmit, to thesecond audio output device 940, reference time information about a timeto start increasing or decreasing the playback speed of the first audiodata through the first short-range communication module 921. Audio datastreamed in real time may be assigned a time index per predeterminedframe, and the first audio output device 920 and the second audio outputdevice 940 may synchronize the audio output timings based on the timeindex. The reference time information may be a criterion for determiningwhether to increase or decrease the playback speed of audio data whenthe time index reaches a specified time index. In addition, since ittakes time to receive operation mode information from the electronicdevice, to determine the playback speed, and to communicate with thesecond audio output device 940, the first processor 923 may generate thereference time information in view of an offset time. For example, thereference time information may be a value of the time index of time atwhich the operation mode information is received plus offset timeinformation. Here, the offset time is provided in view of time toperform data processing for changing the playback speed based oninformation received from the first processor 923 or the secondprocessor 943 and may be predetermined when the audio output device ismanufactured.

According to another embodiment, the electronic device may generatereference time information and may transmit the reference timeinformation to the first audio output device 920 and the second audiooutput device 940. In this case, the first audio output device 920 andthe second audio output device 940 may respectively provide the amountof audio data buffered in the first memory 924 and the amount of audiodata buffered in the second memory 944 to the electronic device.

According to an embodiment, when the operation mode information isreceived from the electronic device and the operation mode is changed(e.g., from a normal mode to a low latency mode or from the low latencymode to the normal mode), the first processor 923 may configure areference period according to the operation mode. The first processor923 may compare the lower of the amount of the first audio data bufferedin the first memory 924 and the amount of the second audio data bufferedin the second memory 944 with the reference period, and may generatereference time information about the time to start decelerated playbackof the first audio data when the lower amount is less than a lower limitof the reference period. Subsequently, the first processor 923 may playthe first audio data at the reference speed, and may decelerate playbackof the first audio data for a specified time period when the time indexof the received first audio data reaches the reference time information.According to another embodiment, the first processor 923 may compare ahigher value of the amount of the first audio data buffered in the firstmemory 924 and the amount of the second audio data buffered in thesecond memory 944 with the reference period. For example, whendecelerated playback is required according to a change in operation modeof the electronic device (e.g., a change from the low latency mode tothe normal mode or a high latency mode or a change from the normal modeto the high latency mode), the first processor 923 may compare thehigher value of the amount of the first audio data and the amount of thesecond audio data with the reference period.

According to an embodiment, the second processor 943 may receive thereference time information from the first audio output device 920through the second short-range communication module 941. The secondprocessor 943 may play the second audio data at the reference speed, andmay decelerate playback of the second audio data for a specified timeperiod when the time index of the received second audio data reaches thereference time information.

According to another embodiment, the second processor 943 may generatereference time information based on the lower value (or higher value) ofthe amount of the first audio data and the amount of the second audiodata. Since the time indexes are synchronized and applied in the firstaudio output device 920 and the second audio output device 940, and thesame offset time is also configured, the reference time informationdetermined respectively by the first processor 923 and the secondprocessor 943 may be the same.

According to an embodiment, the first processor 923 may determine thetime to accelerate or decelerate playback of audio data according to acomparison of the lower of the amount of the first audio data bufferedin the first memory 924 and the amount of the second audio buffered inthe second memory 944 with an upper or lower limit of the referenceperiod. For example, the first processor 923 may calculate time takenfor the lower of the amount of the first audio data buffered in thefirst memory 924 and the amount of the second audio buffered in thesecond memory 944 to reach the lower limit of the reference period indecelerated playback, thereby determining time to decelerate playback.

FIG. 10 illustrates the operations of an electronic device, a firstaudio output device and a second audio output device according to anembodiment.

The method illustrated in FIG. 10 may be performed by the audio outputdevice described above with reference to FIG. 9. Hereinafter, when anelectronic device 1000 is changed from a normal mode to a low latencymode while being connected to an audio output device through short-rangecommunication and playing audio data at a constant reference speed, theoperation of each device will be described.

In operation 1010, when the mode of the audio output device is changedfrom the normal mode to the low latency mode, the electronic device 1000(e.g., the electronic device 101 of FIG. 1) may transmit operation modeinformation to a first audio output device 1002 (e.g., the first audiooutput device 920 of FIG. 9). The first audio output device 1002 mayconfigure a reference period of a buffer memory to the second referenceperiod according to the changed low latency mode.

Here, for the sake of illustrating a concrete example, time index isassumed to be 50.

In operation 1015, the first audio output device 1002 may transmit theoperation mode information to a second audio output device 1004, mayidentify the amount of first audio data buffered in a first memory, andmay transmit the amount of the first audio data to the second audiooutput device.

In operation 1020, the first audio output device 1002 may identify theamount of second audio data buffered in a second memory.

In operation 1030, the first audio output device 1002 may identify theamount of the first audio data buffered in the first memory and mayidentify the lower of the amount of the first audio data buffered in thefirst memory and the amount of the second audio data buffered in thesecond memory. According to another embodiment, when deceleratedplayback of audio data is required (e.g., when the electronic device1000 is changed from the normal mode or the low latency mode to the highlatency mode), the second audio output device 1004 may also identify theamount of the second audio data buffered in the second memory and mayidentify the lower of the amount of the second audio data buffered inthe second memory and the amount of the first audio data buffered in thefirst memory. Since the first audio output device and the second audiooutput device each select the lower amount by comparing the amount ofthe first audio data buffered in the first memory of the first audiooutput device with the amount of the second audio data buffered in thesecond memory of the second audio output device, the target capacity ofthe buffer determined in the first audio output device and the targetcapacity of the buffer determined in the second audio output device maybe the same.

The first audio output device 1002 may compare the identified loweramount (referred to as the minimum buffer or Min buffer) with the secondreference period corresponding to the low latency mode. When theidentified lower value is greater than an upper limit of the secondreference period, the first audio output device 1002 may determine thataccelerated playback is required.

The first audio output device 1002 may generate reference timeinformation about the time to start accelerated playback of audio data.For example, the reference time information may be the value of the timeindex of time when the operation mode information is received plus anoffset time required for the first audio output device and the secondaudio output device to exchange information with each other, and theoffset time may be the time necessary for processing, such as receivingthe operation mode information from the electronic device 1000,determining a playback speed, and communicating with the second audiooutput device 1004 and may be predetermined. Here, the reference timeinformation may include information about timing (e.g., time index=70)to start accelerated playback based on the time index and timing (e.g.,time index=150) to terminate accelerated playback and to switch toconstant-speed playback. In this case, because the time index atoperation 1010 is assumed to be 50, the offset time may be 20.

The timing (e.g., time index=150) to switch to constant-speed playbackmay vary depending on the accelerated playback speed and the deceleratedplayback speed. For example, the time index, which is 150 at anacceleration of 1.1, may be changed to 130 at an acceleration of 1.2.

In operation 1035, the second audio output device 1004 may identify thelower of the amount of the first audio data and the amount of the secondaudio data and may generate reference time information based on thelower amount. Since the time indexes are synchronized and applied in thefirst audio output device 1002 and the second audio output device 1004,and the same offset time is also configured, and the reference timeinformation determined respectively by the first audio output device1002 and the second audio output device 1004 may be the same. Accordingto an embodiment, the second audio output device 1004 may adjust theplayback speed according to the reference time information received fromthe first audio output device 1002, rather than directly generatingreference time information, in which case operation 1035 may be omitted.

In operation 1040, the first audio output device 1002 may transmit thegenerated reference time information to the second audio output device1004. Operation 1040 may be omitted when the second audio output device1004 generates reference time information (e.g., operation 1035). Whenoperation 1040 is omitted, the first audio output device and the secondaudio output device may each calculate the same reference timeinformation based on the accelerated and decelerated playback speeds andbuffer information about the first audio output device and the secondaudio output device, which were previously exchanged between the firstaudio output device 1002 and the second audio output device 1004.

In operation 1050, even though accelerated playback is determined andthe reference time information is generated, the first audio outputdevice 1002 may maintain constant-speed playback at normal playbackspeed until the time index reaches the time index 70 which is thedetermined reference time information. Likewise, in operation 1055, thesecond audio output device 1004 may also maintain constant-speedplayback.

In operation 1060, when the time index reaches the time index 70, thefirst audio output device 1002 may accelerate playback of the firstaudio data at a specified speed (e.g., 1.1 times a reference speed).Likewise, the second audio output device 1004 may accelerate playback ofthe second audio data at the same speed.

In operation 1070, when the time index reaches a time index 150, thefirst audio output device 1002 may terminate the accelerated playbackand may play the first audio data back at the constant normal speed.Likewise, the second audio output device 1004 may terminate theaccelerated playback of the second audio data and play the second audiodata at the constant normal speed.

FIG. 11 illustrates reference periods of buffer memories of a firstaudio output device and a second audio output device according to anembodiment.

According to an embodiment, the first audio output device (e.g., thefirst audio output device 920 of FIG. 9) may buffer first audio datareceived from an electronic device in a first memory 1124, and thesecond audio output device (e.g., the second audio output device 940 ofFIG. 9) may buffer second audio data received from the electronic deviceor the first audio output device in a second memory 1144.

According to an embodiment, the first audio output device (e.g., a firstprocessor) may receive the amount of the second audio data buffered inthe second memory 1144 of the second audio output device through a firstshort-range communication module, may identify the lower of the amountof the first audio data buffered in the first memory 1124 of the firstaudio output device and the amount of the second audio data buffered inthe second memory 1144 of the second audio output device, and maycompare the lower amount with a reference period corresponding to thecurrent operation mode of the electronic device. Since the first audiooutput device and the second audio output device are wirelesslyconnected, the amounts of audio data buffered respectively in the firstmemory 1124 and the second memory 1114 may be different depending onwireless environments of the respective devices. For example, as shownin FIG. 11, the amount 1151 of audio data buffered in the first memory1124 may be less than the lower limit 1126 (or level 1) of the referenceperiod and may thus be outside the reference range, and the amount 1152of audio data buffered in the second memory 1144 may be between thelower limit 1146 and the upper limit 1147 (or level 2) of the referenceperiod and may thus be within the reference period. In this case, thefirst audio output device may identify that the lower of the amount 1151of the first audio data buffered in the first memory 1124 and the amount1152 of the second audio data buffered in the second memory 1144 is theamount 1151 of audio data buffered in the first memory 1124.

Here, since the identified amount is outside the reference period, thefirst audio output device may determine to decelerate playback of audiodata, may generate reference time information for decelerated playback,and transmit the reference time information to the second audio outputdevice. According to another embodiment, the second audio output devicemay generate reference time information by using the amount 1151 of thefirst audio data, the amount 1152 of the second audio data, and a setoffset time.

Subsequently, when the reference time is reached, the first audio outputdevice and the second audio output device may decelerate playback ofaudio data for a specified time interval.

An audio output device 300 according to an embodiment may include: ashort-range communication module 310 configured to perform short-rangewireless communication; a memory 340 configured to buffer audio datareceived from an external electronic device through the short-rangecommunication module 310; an audio output unit 320 configured to outputthe audio data; and a processor 330 operatively connected to theshort-range communication module 310, the memory 340, and the audiooutput unit 320, wherein the processor 330 may be configured to: receiveoperation mode information related to a function being executed in theexternal electronic device from the external electronic device throughthe short-range communication module 310; configure a reference periodcorresponding to the amount of the audio data buffered in the memory 340based on the operation mode information; and determine the playbackspeed of the audio data to be output through the audio output unit 320unit by comparing the amount of the buffered audio data with theconfigured reference period.

According to an embodiment, the processor 330 may be configured to:determine the playback speed of the audio data to be a second playbackspeed faster than a first playback speed, which is a reference speed,when the amount of the buffered audio data is an amount corresponding togreater than an upper limit of the reference period; and determine theplayback speed of the audio data to be a third playback speed slowerthan the first playback speed when the amount of the buffered audio datais an amount corresponding to less than a lower limit of the referenceperiod.

According to an embodiment, the processor 330 may be configured to:output the audio data at the first playback speed when the amount of thebuffered audio data reaches an amount corresponding to the upper limitof the reference period after outputting the audio data at the secondplayback speed; and output the audio data at the first playback speedwhen the amount of the buffered audio data reaches an amountcorresponding to the lower limit of the reference period afteroutputting the audio data at the third playback speed.

According to an embodiment, when the playback speed of the audio data isdetermined to be the second playback speed or the third playback speed,the processor 330 may be configured to output the audio data at thesecond playback speed or the third playback speed for a specified timeperiod, and to output the audio data at the first playback speed after alapse of the specified time period.

According to an embodiment, the operation mode information may relate toa normal mode, a low latency mode, and a high latency mode.

According to an embodiment, the low latency mode may be configured whenthe external electronic device executes a specified application, when adisplay of the external electronic device is turned on, and/or when theexternal electronic device receives a touch input.

According to an embodiment, the high latency mode may be configured whena display of the external electronic device is turned off and/or whenthe display does not receive a touch input for a certain period.

According to an embodiment, the processor 330 may be configured to:compare the amount of the buffered audio data with a predetermined firstreference period when the external electronic device operates in thenormal mode based on the received operation mode information; comparethe amount of the buffered audio data with a predetermined secondreference period when the external electronic device operates in the lowlatency mode; and compare the amount of the buffered audio data with apredetermined third reference period when the external electronic deviceoperates in the high latency mode.

According to an embodiment, the second reference period may have a lowerlimit lower than a lower limit of the first reference period and mayhave an upper limit lower than an upper limit of the first referenceperiod, and the third reference period may have a lower limit higherthan the lower limit of the first reference period and may have an upperlimit higher than the upper limit of the first reference period.

According to an embodiment, when the external electronic device operatesin the low latency mode, the processor 330 may be configured to outputthe audio data at a second playback speed slower than a first playbackspeed, which is a reference speed, when the amount of the buffered audiodata is less than an amount corresponding to a first lower limit of thesecond reference period, and to output the audio data at a thirdplayback speed slower than the second playback speed when the amount ofthe buffered audio data is less than an amount corresponding to a secondlower limit lower than the first lower limit of the second referenceperiod.

According to an embodiment, the processor 330 may be configured to:exchange the amount of first audio data buffered in the memory 340 withthe amount of second audio data buffered in a memory of an externalaudio output device through the short-range communication module 310;and compare a lower of the amount of the buffered audio data and theamount of the second audio data buffered in the memories of therespective audio output devices with the reference period.

According to an embodiment, the processor 330 may be configured to:determine reference time information about a time to start increasing ordecreasing the playback speed of the audio data; and transmit thereference time information to the external audio output device throughthe short-range communication module 310.

According to an embodiment, the processor 330 may be configured toincrease or decrease the playback speed of the audio data when a timeindex reaches the reference time information.

According to an embodiment, the reference time information may be avalue of a time index of a time when the operation mode information isreceived plus an offset time.

According to an embodiment, the processor 330 may be configured toreceive acceleratedly processed audio data from the external electronicdevice when the amount of the buffered audio data is less than an amountcorresponding to a lower limit of the configured reference period.

FIG. 12 is a flowchart illustrating a method for controlling an audiooutput speed according to an embodiment.

In operation 1210, an audio output device may perform an initializationoperation. Here, the current state may be configured to be 0, and anaudio output device may play audio data at the constant normal speed inthe current state of 0.

In operation 1220, the audio output device (e.g., the audio outputdevice 900 of FIG. 9) may receive operation mode information from anelectronic device (e.g., the electronic device 101 of FIG. 1).

In operation 1230, the audio output device may identify whether thereceived operation mode is changed from the high latency mode to thenormal mode or the low latency mode or from the normal mode to the lowlatency mode. For example, the electronic device, which was operating inthe normal mode, may be changed to the low latency mode according toexecution of a specific application or a user input, or the electronicdevice, which is operating was the high latency mode due to poorwireless environment between the electronic device and the audio outputdevice during execution of a music application, may be change to thenormal mode as the wireless environment is improved.

When the operation mode of the electronic device is changed from thehigh latency mode to the normal mode or the low latency mode or from thenormal mode to the low latency mode in operation 1230, the current statemay be configured to be 2 in operation 1240. Here, the current state of2 may be a state in which accelerated playback is required according tothe change in the operation mode.

In operation 1235, the audio output device may identify whether thereceived operation mode is changed from the low latency mode to thenormal mode or the high latency mode or from the normal mode to the highlatency mode. For example, when the wireless environment between theelectronic device and the audio output device is deteriorated duringexecution of the music application, the electronic device may be changedto the high latency mode.

When the operation mode of the electronic device is changed from the lowlatency mode to the normal mode or the high latency mode or from thenormal mode to the high latency mode in operation 1235, the currentstate may be configured to be 1 in operation 1245. Here, the currentstate of 1 may be a state in which decelerated playback is requiredaccording to the change in the operation mode.

In operation 1250, the audio output device may generate reference timeinformation. The reference time information may be a criterion fordetermining whether to accelerate or decelerate playback of audio datawhen a specific time index is reached and may be a value of the timeindex of time at which the operation mode information is received plusoffset time information. The audio output device may identify the lowerof the amount of first audio data buffered in the first memory of afirst audio output device and the amount of second audio data bufferedin the second memory of a second audio output device, may compare thelower amount with the reference period of the current operation mode ofthe electronic device, and may determine whether to accelerate ordecelerate playback according to a comparison result. According toanother embodiment, when in a change to an operation mode in whichdecelerated playback is required (e.g., a change from the normal mode tothe high latency mode), the audio output device may compare the higherof the amount of the first audio data and the amount of the second audiodata with the reference period and may determine whether to decelerateplayback.

According to an embodiment, the first audio output device may transmitthe generated reference time information to the second audio outputdevice, and the second audio output device may determine the timing ofaccelerated playback or decelerated playback according to the receivedreference time information. According to another embodiment, the secondaudio output device may generate reference time information based on theamount of the first audio data and the amount of the second audio data.Since the same offset time is configured, the reference time informationgenerated by the first audio output device and the second audio outputdevice may have the same start time and the same end time. In operation1260, the audio output device may identify whether a current time indexreaches the start time of acceleration or deceleration of the referencetime information. Since the reference time information is the value ofthe time index of the time at which the operation mode information isreceived plus the offset time information, the audio output device maymaintain constant-speed playback until reaching the start time inoperation 1265. Subsequently, the audio output device may startaccelerated or decelerated playback according to the current state(e.g., 1 or 2) when reaching the start time of the reference timeinformation.

When the current time index reaches the start time of the reference timeinformation, the audio output device may identify whether the currentstate is 2 in operation 1270. Since the current state of 2 is a state inwhich accelerated playback is required, the audio output device mayaccelerate playback of audio data in operation 1280.

When the current state is 1 rather than 2, in which decelerated playbackis required, the audio output device may decelerate playback of audiodata in operation 1285.

In operation 1290, the audio output device may identify whether thecurrent time index reaches the end time of the reference timeinformation. When the end time is reached, the audio output device mayplay audio data back at the constant normal speed in operation 1295.

FIG. 13 is a flowchart illustrating a method for controlling an audiooutput speed according to an embodiment.

FIG. 13 illustrates an embodiment in which an electronic device performsaccelerated processing of audio data and transmits the audio data to anaudio output device for accelerated playback of audio data. Theillustrated method may be applied to an audio output device includingone audio output unit or a plurality of audio output units connected viaa cable (e.g., the audio output device of FIG. 2A and the audio outputdevice of FIG. 3) and may also be applied to an audio output deviceincluding a plurality of audio output units which are physicallyseparated and wirelessly connected (e.g., the audio output device 220 ofFIG. 2B and the audio output device 900 of FIG. 9).

In operation 1310, the audio output device may perform an initializationoperation. Here, the current state may be configured to be 0, and anaudio output device may play audio data at the constant normal speed inthe current state of 0.

In operation 1320, the electronic device may receive operation modeinformation from a framework. Here, the operation mode may include anormal mode, a low latency mode, and a high latency mode.

In operation 1330, the electronic device may identify whether the highlatency mode is changed to the normal mode or the low latency mode orthe normal mode is changed to the low latency mode. In a change from thehigh latency mode to the normal mode or the low latency mode or in achange from the normal mode to the low latency mode, the current statemay be configured to be 2 in operation 1340. Here, the current state of2 may be a case in which accelerated playback is required.

In operation 1350, the electronic device may generate reference timeinformation. Here, the reference time information may define a periodfor the start and end times of accelerated playback.

In operation 1360, the audio output device may identify whether thecurrent time index has reached the start time of acceleration of thereference time information. The audio output device may receive audiodata of the same transmission tick from the electronic device until thecurrent time index reaches the start time of acceleration of thereference time information. When the current time index reaches thestart time of acceleration of the reference time information, theelectronic device may perform accelerated processing of audio data andmay transmit the audio data to the audio output device according to anincreased transmission tick. In operation 1370, the audio output devicemay receive and output the acceleratedly processed audio data from theelectronic device.

In operation 1380, when the time index reaches the end time ofacceleration of the reference time information, the electronic devicemay transmit audio data back at the constant normal speed according toan original transmission tick. In operation 1390, the audio outputdevice may play the received audio data at the constant speed.

An audio output speed control method according to an embodiment mayinclude: receiving operation mode information related to a functionbeing executed in an external electronic device from the externalelectronic device through short-range communication; configuring areference period corresponding to an amount of audio data buffered in amemory 340 based on the operation mode information; and determining aplayback speed of the audio data to be output through an audio outputunit 320 by comparing the amount of the buffered audio data with theconfigured reference period.

According to an embodiment, the determining of the playback speed mayinclude: determining the playback speed of the audio data to be a secondplayback speed faster than a first playback speed, which is a referencespeed when the amount of the buffered audio data is an amountcorresponding to greater than an upper limit of the reference period; ordetermining the playback speed of the audio data to be a third playbackspeed slower than the first playback speed when the amount of thebuffered audio data is an amount corresponding to less than a lowerlimit of the reference period.

According to an embodiment, the operation mode information may relate toa normal mode, a low latency mode, and a high latency mode.

According to an embodiment, the low latency mode may be configured whenthe external electronic device executes a specified application, when adisplay of the external electronic device is turned on, and/or when theexternal electronic device receives a touch input.

According to an embodiment, the high latency mode may be configured whena display of the external electronic device is turned off and/or whenthe display does not receive a touch input for a certain period.

Certain of the above-described embodiments of the present disclosure canbe implemented in hardware, firmware or via the execution of software orcomputer code that can be stored in a recording medium such as a CD ROM,a Digital Versatile Disc (DVD), a magnetic tape, a RAM, a floppy disk, ahard disk, or a magneto-optical disk or computer code downloaded over anetwork originally stored on a remote recording medium or anon-transitory machine readable medium and to be stored on a localrecording medium, so that the methods described herein can be renderedvia such software that is stored on the recording medium using a generalpurpose computer, or a special processor or in programmable or dedicatedhardware, such as an ASIC or FPGA. As would be understood in the art,the computer, the processor, microprocessor controller or theprogrammable hardware include memory components, e.g., RAM, ROM, Flash,etc. that may store or receive software or computer code that whenaccessed and executed by the computer, processor or hardware implementthe processing methods described herein.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the present disclosure as defined by the appendedclaims and their equivalents.

What is claimed is:
 1. An audio output device comprising: a short-range communication module configured to perform short-range wireless communication; a memory configured to buffer audio data received from an external electronic device through the short-range communication module; an audio output unit configured to output the audio data; and a processor operatively connected to the short-range communication module, the memory, and the audio output unit, wherein the processor is configured to: receive operation mode information related to a function being executed in the external electronic device from the external electronic device through the short-range communication module; configure a reference period corresponding to an amount of the audio data buffered in the memory based on the operation mode information; and determine a playback speed of the audio data to be output through the audio output unit by comparing the amount of the buffered audio data with the configured reference period.
 2. The audio output device of claim 1, wherein the processor is further configured to: determine the playback speed of the audio data to be a second playback speed faster than a first playback speed, which is a reference speed, when the amount of the buffered audio data is an amount corresponding to greater than an upper limit of the reference period; and determine the playback speed of the audio data to be a third playback speed slower than the first playback speed when the amount of the buffered audio data is an amount correspond to less than a lower limit of the reference period.
 3. The audio output device of claim 2, wherein the processor is further configured to: output the audio data at the first playback speed when the amount of the buffered audio data reaches an amount corresponding to the upper limit of the reference period after outputting the audio data at the second playback speed; and output the audio data at the first playback speed when the amount of the buffered audio data reaches an amount corresponding to the lower limit of the reference period after outputting the audio data at the third playback speed.
 4. The audio output device of claim 2, wherein, when the playback speed of the audio data is determined to be the second playback speed or the third playback speed, the processor is further configured to output the audio data at the second playback speed or the third playback speed for a specified time period, and to output the audio data at the first playback speed after a lapse of the specified time period.
 5. The audio output device of claim 1, wherein the operation mode information relates to a normal mode, a low latency mode, and a high latency mode.
 6. The audio output device of claim 5, wherein the low latency mode is configured when the external electronic device executes a specified application, when a display of the external electronic device is turned on, and/or when the external electronic device receives a touch input.
 7. The audio output device of claim 5, wherein the high latency mode is configured when a display of the external electronic device is turned off and/or when the display does not receive a touch input for a certain period.
 8. The audio output device of claim 5, wherein, to compare the amount of the buffered audio data with the configured reference period, the processor is further configured to: compare the amount of the buffered audio data with a predetermined first reference period when the external electronic device operates in the normal mode based on the received operation mode information; compare the amount of the buffered audio data with a predetermined second reference period when the external electronic device operates in the low latency mode; and compare the amount of the buffered audio data with a predetermined third reference period when the external electronic device operates in the high latency mode.
 9. The audio output device of claim 8, wherein the second reference period has a lower limit lower than a lower limit of the first reference period and has an upper limit lower than an upper limit of the first reference period, and the third reference period has a lower limit higher than the lower limit of the first reference period and has an upper limit higher than the upper limit of the first reference period.
 10. The audio output device of claim 8, wherein, when the external electronic device operates in the low latency mode, the processor is further configured to output the audio data at a second playback speed slower than a first playback speed, which is a reference speed, when the amount of the buffered audio data is less than an amount corresponding to a first lower limit of the second reference period, and to output the audio data at a third playback speed slower than the second playback speed when the amount of the buffered audio data is less than an amount corresponding to a second lower limit lower than the first lower limit of the second reference period.
 11. The audio output device of claim 1, wherein the processor is further configured to: receive an amount of second audio data buffered in a memory of an external audio output device through the short-range communication module; and perform an additional comparison of comparing a lower of the amount of the buffered audio data buffered in the memory of the audio output device and the amount of the second audio data with the reference period.
 12. The audio output device of claim 11, wherein the processor is further configured to transmit reference time information about a time to start increasing or decreasing the playback speed of the audio data to the external audio output device through the short-range communication module.
 13. The audio output device of claim 12, wherein the processor is further configured to increase or decrease the playback speed of the audio data when a time index reaches the reference time information.
 14. The audio output device of claim 12, wherein the reference time information is a value of a time index of a time when the operation mode information is received plus an offset time.
 15. The audio output device of claim 1, wherein the processor is further configured to receive acceleratedly processed audio data from the external electronic device when the amount of the buffered audio data is less than an amount corresponding to a lower limit of the configured reference period.
 16. A method for controlling an audio output speed, the method comprising: receiving operation mode information related to a function being executed in an external electronic device from the external electronic device through short-range communication; configuring a reference period corresponding to an amount of audio data buffered in a memory based on the operation mode information; and determining a playback speed of the audio data to be output through an audio output unit by comparing the amount of the buffered audio data with the configured reference period.
 17. The method of claim 16, wherein the determining of the playback speed comprises: determining the playback speed of the audio data to be a second playback speed faster than a first playback speed, which is a reference speed, when the amount of the buffered audio data is an amount corresponding to greater than an upper limit of the reference period; and/or determining the playback speed of the audio data to be a third playback speed slower than the first playback speed when the amount of the buffered audio data is an amount corresponding to less than a lower limit of the reference period.
 18. The method of claim 16, wherein the operation mode information relates to a normal mode, a low latency mode, and a high latency mode.
 19. The method of claim 18, wherein the low latency mode is configured when the external electronic device executes a specified application, when a display of the external electronic device is turned on, and/or when the external electronic device receives a touch input.
 20. The method of claim 18, wherein the high latency mode is configured when a display of the external electronic device is turned off and/or when the display does not receive a touch input for a certain period. 